Adding to the above advice. If you have DIVX try uninstalling it. Also if you run a 3rd party Win/Shell extension (like Lite Step and or Windows Blinds uninstall it or exit out of the running app in explorer.exe) and see if the problem is still here. One or the other, or both should fix it for you. Both of these things have been know problems recently for the error message you indicated concerning SP2.